Heretofore in drilling offshore wells the initial portion of the wellbore nearest the ocean floor had set therein a conductor pipe through which further well operations were carried out. Generally this conductor is installed in one of two methods depending on the bottom soils. If the soils are soft (normally compacted) the conductor can be jetted into the sea floor to a depth that will provide adequate support. If the soils are hard (overly compacted and too hard to jet) the conductor hole must be drilled. Often, in the latter situation the conductor pipe has connected to the upper end thereof a landing base which was designed to rest on the surface of the floor of the body of water, e.g., the ocean floor, to support the conductor. Such a combination of well conductor and landing base is fully and completely disclosed in U.S. Pat. No. 3,143,172, the disclosure of which is incorporated herein by reference.
In some areas of the world, such as where the bottom portion of the conductor hole must be drilled, there is at least a top layer of the floor on which the landing base is to rest is so soft and flowable that it is a semi-fluid material and the landing bases of the prior art simply sink into this floor layer just as they sink in the water above the floor layer. Also in such situations additional axial support at the mud line can be necessary. Thus, in these situations the prior art landing bases provide essentially no support for the conductor. In these situations proper setting of the well conductor is quite important in order to keep the flowable floor layer from flowing into any wellbore drilled. Otherwise no headway is made with the wellbore into a more competent formation which will not flow into the wellbore since, in the absence of the well conductor, the flowable layer fills in the wellbore as fast as it is drilled.
Accordingly, where the floor through which a wellbore is to pass is soft and flowable, it is highly desirable to have apparatus and a method which will allow for the positive supporting of well conductor in the soft flowable floor layer.